23 cents at Ace hardware. Called a K-clip I think. Keeps the shoulder belt attached to the lap belt. Had to file it down a little on both sides to make it fit.

Looks good, but, I'm wondering if the ends of that K-clip will cause wear on the cloth belt?  Have you done some searching to see if you can find a retaining ring that will fit ?  Something like the one below.

Yeah, I saw those in the next drawer, they all seemed too big or too small.. Might be something better than the K-clip, though.

I filed the ends to unsharpen them, mostly so I wouldn't scratch myself. The fold-over on the lap belt seems to cover it pretty well, though. Tried rubber washers before, worked for a while but eventually fell off.